Electroacupuncture on Baihui (DU20) and Xuehai (SP10) acupoints alleviates psoriatic inflammation by regulating neurotransmitter substance P- Neurokinin-1 receptor signaling

Abstract

Background: At present, acupuncture-related practices have been widely used to treat psoriasis. In our study, we investigated the effect and explored the mechanism of electroacupuncture (EA) on acupoints Baihui (DU20) and Xuehai (SP10) for the treatment of psoriasis.

Methods: Imiquimod-induced psoriasis-like mouse model was used in this study. Mice were treated with electroacupuncture at DU20 and SP10 (depth of 2-3 mm, frequency of 2/15 Hz, intensity of 0.5-1.0 mA, 10 min/day). The severity of psoriasis-like lesions for each group was assessed. In addition, histological analysis of the lesions were performed. The levels of inflammatory cytokines were determined using Elisa. The expression levels of Substance P (SP) and NK1R were measured using Western blotting. In addition, NK1R inhibitor was administrated to evaluate the target of electroacupuncture in our mouse model.

Results: Electroacupuncture significantly alleviated IMQ-induced skin lesions and epidermal thickness, accompanied with reduced keratinocyte proliferation, CD3⁺, CD4⁺, and CD8⁺ T cells infiltration. The reduced levels of inflammatory cytokines was observed after electroacupuncture treatment. In addition, electroacupuncture inhibited the expression levels of SP and NK1R. NK1R inhibitor could ameliorate lesional symptoms and suppress epidermal thickening and CD3⁺, CD4⁺, and CD8 + T cell infiltration.

Conclusions: Electroacupuncture relieved psoriasis-like inflammation and T cell infiltration. This therapeutic action was likely mediated by the modulation of Substance P and its receptor NK1R.

Keywords: Electroacupuncture; Inflammation; Neurokinin-1 receptor; Psoriasis; Substance P.

Graphical abstract

Fig. 1

Diagram of the experimental protocol. Except for the Ctrl group, all other groups were treated topically with 62.5 mg IMQ cream (5%) on days 1–6. Electroacupuncture treatment was performed daily from day 4–6 for the electroacupuncture group.

Fig. 2

Electroacupuncture ameliorates psoriasis-like inflammation in IMQ-Induced Mice. (A) Skin lesions in mice on day seven after IMQ administration. (B) Psoriasis Area Severity Index (PASI) scores for skin damage, i.e., scaling, thickness, and erythema. Cumulative score (scaling + thickness + erythema). (C) HE at 200 × . (D) The epidermal thickness of the dorsal skin. Scale bar = 50 μm. Data are presented as the mean ± SD (n = 8/group). ∗∗ <0.01 vs Ctrl; # <0.05vs IMQ, ## <0.01 vs IMQ.

Fig. 3

Electroacupuncture alleviates keratinocyte proliferation and inflammatory cell infiltration in psoriatic mice. (A) Expression of Ki67 in the skin cells of mice for each group (IF) Scale bar = 50 μm. (B–D) IHC staining for CD3, CD8, and CD4. (E–H) Statistical analysis of the number of Ki67+, CD3⁺, CD4⁺, and CD8⁺ cells in the epidermis. Data are presented as mean ± SD (n = 5/group). Scale bar = 200 μm ∗∗ <0.01 vs Ctrl; # <0.05vs IMQ, ## <0.01 vs IMQ.

Fig. 4

Electroacupuncture reduced the expression levels of inflammatory cytokines in the serum of psoriasis-like mouse models. Data are presented as mean ± SD(A-K) n = 5/group. ∗<0.05 vs Ctrl, ∗∗ <0.01 vs Ctrl; # <0.05vs IMQ, ## <0.01 vs IMQ.

Fig. 5

Electroacupuncture inhibits the expression levels of neurotransmitter SP and its receptor NK1R in imiquimod-induced psoriasis-like mouse models. (A) Immunofluorescence staining of SP.(B) Representative immunoblots of SP and NK1R by western blot. (C) Relative protein expression levels and statistical analysis for SP and NK1R levels. Data are presented as mean ± SD (n = 4/group). ∗<0.05 vs Ctrl, ∗∗ <0.01 vs Ctrl; # <0.05vs IMQ, ## <0.01 vs IMQ.

Fig. 6

Correlation analysis between expression levels of inflammatory cytokines and SP. A: IL17A vs SP; B: IL-22 vs SP. R: Pearson's correlation. (Green: Ctrl, Yellow: EN, Blue: MTX, Red: IMQ ）

Fig. 7

Electroacupuncture and NK1R inhibitors reduced IMQ-induced skin thickening and inflammatory cell infiltration. (A) Skin lesions in mice on day 6 of IMQ administration. (B) HE staining (200 × ), Scale bar = 100 μm. (C–E) IHC staining for CD3, CD8, and CD4. Data is presented as mean ± SD (n = 3–4/group) Scale bar = 100 μm∗ <0.05 vs Ctrl, ∗∗ <0.01 vs Ctrl; # <0.05 vs IMQ, ## <0.01 vs IMQ. (F) Epidermal thickness for each group. (G–I) Statistical analysis of the number of CD3⁺, CD4⁺, and CD8⁺ cells in the epidermis.

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